Is spring really — finally — here?

It’s far from clear whether the weather plans to cooperate, but spring arrives – at least technically – on Friday.

The spring equinox arrives on Friday, marking the start of the spring season for the Northern Hemisphere and autumn in the Southern Hemisphere. On the equator, the sun will be directly above midday. The equinoxes are the only times when the North and South poles are illuminated at the same time by the sun.

The equinoxes have been marked and celebrated around the world for centuries. In Japan, for example, the day of the vernal equinox is a public holiday. At the Mayan site of Chichen Itza in Mexico, people gather during the equinox to watch the sun create a shadow pattern that resembles a serpent descending a pyramid called El Castillo.

But what is happening in the skies? Here’s what you need to know about Earth’s orbit.

What is the equinox?

When Earth moves around the sun, it does so at an angle, causing the sun’s heat and light to fall unevenly on the northern and southern halves of the planet for most of the year.

But during the equinox, Earth’s tilt is neither toward the sun nor away from the sun, so the northern and southern hemispheres receive an equal amount of sunlight. The sun rises almost exactly due east and sets almost exactly due west.

The word equinox comes from two Latin words meaning equal and night. Indeed, at the equinox, day and night last almost the same length, although you may have a few extra minutes, depending on where you are on the planet.

The northern hemisphere’s autumnal – or fall – equinox can occur between September 21 and 24, depending on the year. Its spring – or vernal – equinox can arrive between March 19 and 21.

The exact time of the equinox is when the sun is directly above the equator. For 2026, it is Friday, March 20 at 10:46 a.m. EST. From there, the days will get a little longer each day in the northern hemisphere – and shorter in the southern hemisphere – until the June solstice.

What is the solstice?

The solstices mark the times when the Earth’s tilt is most extreme, either towards or away from the sun. This means that the hemispheres receive very different amounts of sunlight, and the days and nights are most unequal.

At the northern hemisphere’s summer solstice, the upper half of the Earth is tilted toward the sun, creating the longest day and shortest night of the year. The summer solstice falls between June 20 and 22. This year it’s the 21st.

The opposite occurs at the Northern Hemisphere’s winter solstice: the upper half of Earth is farthest from the sun, leading to the shortest day and longest night of the year. The winter solstice falls between December 20 and 23.

What is the difference between meteorological and astronomical seasons?

These are just two different ways of dividing the year.

While astronomical seasons depend on how the Earth moves around the sun, meteorological seasons are defined by the weather. Meteorologists break the year into three-month seasons based on annual temperature cycles. According to this calendar, spring begins on March 1, summer on June 1, autumn on September 1, and winter on December 1.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute’s Department of Science Education and the Robert Wood Johnson Foundation. The AP is solely responsible for all content.